This invention relates to an apparatus for detecting faults during the manufacturing of elongate material. In particular the apparatus is designed to detect faults that may occur during the manufacture of coated wire and cable including optical fibre cable.
Enamel coated wire is used extensively in the windings of electric motors and transformers. This wire ranges from a very fine diameter of 0.019 mm to a thicker diameter of 4.7 mm.
The wire is produced at high speed in great lengths, and for instance, a drum of wire can weigh half a tonne and include 800 km of wire. The known machinery that is used to manufacture this wire, whilst it has been efficient, is not perfect and there is often an occurrence of faults or defects in the wire. Faults or defects include:
Blisters
Bare patches
Pin holes
Rippling
Enamel depth inconsistency
Curing variation (by colour)
Eccentricity of wire in enamel
Ovality of the wire and enamel
Absolute dimensions of wire and enamel
It is extremely difficult to detect the existence of faults in the wire and often these faults are only detected when the wire is in its end use. Faulty windings in an electric motor or transformer can be very dangerous and it is thus agreed by the industry that there is a need to detect faults in the wire during the production process so that for any finished spool of wire there can be an indication of the existence of faults, the characteristic of the faults and the position of faults along the length of wire as wound on the spool.
It is these problems and their solution that has brought about the present invention.
According to one aspect of the present invention there is provided apparatus for detecting faults in the exterior surface of elongate material comprising an optical head through which the material passes, the optical head including means to emit light onto the material, means to collect reflected light from the material and means to monitor changes in the reflected light to indicate the presence of faults.
In one embodiment the means to emit light comprises light sources positioned around the material in a first single plane and the means to collect light comprises receivers positioned around the material in a second single plane.
Preferably the light sources transmit light to the material at a specific angle, and the means to collect light are positioned off the line of specular reflection. Specifically the incident angle of the light is 65xc2x0 to the axis of the material, and the means to collect light are at an angle of 90xc2x0 to the axis of the material.
In a preferred embodiment the receivers are mounted around a body with a central light absorbing chamber, the chamber absorbing light not reflected by the material. The means to monitor changes may comprise analogue circuitry to provide an electrical signal, means to amplify and filter the signal, the signal being passed to a processor that can monitor abrupt changes in the signal and characterise the changes and the timing of the changes using digital means.
In a second embodiment the means to emit light comprises at least two coloured light sources positioned around the material in a single plane and means to collect reflected light arranged in the same single plane. Preferably, the means to collect light monitors the change in colour intensity of the reflected light.
In accordance with a further aspect of the present invention there is provided a method of detecting faults in the exterior surface of elongate material comprising passing the material through an optical head, transmitting a light signal to the material, collecting the reflected light and monitoring the reflected light to provide an indication of the existence of a fault in the exterior surface of the material.
The present invention has an objective the provision of a piece of apparatus that can be placed at the end of the production line that will monitor the wire before it is wound up onto the take-up spool. The apparatus will view the wire as it passes and monitor the existence of faults including characteristics of the type of fault, whilst at the same time record where the fault is along the length of the wire. The apparatus will use a computer to monitor and record these parameters. The invention aims to provide a comparatively simply yet effective means of monitoring faults which can be adapted to be used within existing production lines and will thus provide the manufacturers of wire of this kind with a ready indication of the state and quality and characteristics of each spool of wire.